The invention relates to a device for optically measuring an object.
Such devices comprise an interferometer with a light source and a detector. The light source emits a light beam, that is typically split via a beam splitter in the interferometer into a working beam and a reference beam. The working beam is guided to a measuring spot on the object to be measured, if necessary via additional optic components, such as mirrors or lenses. The working beam is at least partially reflected at the object, returns into the beam path of the interferometer, and is guided to the detector.
The reference beam is also guided to the detector, so that on the detector interference occurs between the working beam and the reference beam.
The detector is connected to a signal processing unit, which determines motion data of the object from the measuring signals of the detector. This is possible because the working beam is influenced by a motion of the object based on the Doppler-effect and thus by evaluating the detector signals conclusions can be drawn for the motion of the object, for example the speed of motion. Such devices are usually called Laser-Doppler vibrometers or simply vibrometers.